부하를 고려한 태양열온수시스템의 일간 집열효율에 대한 실험적 분석

이경호(Lee Kyoung-Ho),주홍진(Joo Hong-Jin),윤응상(Yoon Eung-Sang),곽희열(Kwak Hee-Youl) 한국태양에너지학회 2012 한국태양에너지학회 논문집 Vol.32 No.2

This paper describes an experimental study on efficiency of solar collector in solar water heating system connected to hourly water heating load. In general, the functional form of solar efficiency is expressed as a function of fluid temperature entering solar collector, ambient temperature, and solar irradiance. When energy saving from solar heating of water heating system is analyzed on a long-term basis such as one year with given solar irradiance data, simplified analysis is more convenient than detailed system simulation for quick assessment. However, the functional form of the efficiency is not convenient for approximately simplified energy analysis because the inlet temperature can be obtained through a detailed system simulation. In the study, solar collector efficiency is obtained with various daily water heating loads and daily solar irradiance using experimental tests. The study also considers large residential buildings such as apartment buildings for application of solar water heating systems. From test results, it is found that daily solar collector efficiency is proportional to daily water heating loads and daily solar irradiance. The data obtained from the study can be utilized to find a functional relation between daily solar irradiance and daily heating load instead of collector inlet temperature for application of solar collector efficiency to long-term approximated energy analysis of solar heating system.

소규모 열네트워크기반 분산형 열 프로슈머 구현을 위한 직팽식 태양열 히트펌프 적용 가능성 분석

김민휘,김득원,이동원,허재혁 대한설비공학회 2020 설비공학 논문집 Vol.32 No.12

In this study, the feasibility of a direct-expansion solar heat pump for a distributed thermal prosumer in a small-scale thermal network was investigated. In this analysis, a small-scale thermal network for cooling, heating, and hot water established in Jincheon eco-friendly energy town was selected as the test site, and a daycare center in town was also selected as a target building for heat prosumer. The direct-expansion solar heat pump was selected to serve and generate excess heat, and control logic was developed to facilitate the production and delivery of excess heat. In order to simulate the operation of the direct-expansion solar heat pump, an operation model was developed via ANOVA based on the operation data derived from the literature. Simulations were based on the derived model and the operation parameters of the Jincheon eco-friendly energy town. As a result, the direct-expansion solar heat pump showed a COP of 3.5 annually. The amount of heat supplied for domestic hot water from the central management center in the town was 105 MWh/y, and the amount of electric energy consumed by the electric heater located in each building for domestic hot water supply was 37.4 MWh/y. It was predicted that 51.6% of the electric energy consumption for serving domestic hot water could be reduced using the direct-expansion solar heat pump in the daycare center as the thermal prosumer. 본 연구에서는 단일 건물에서의 신재생 열에너지 생산시스템의 적용 한계를 극복하기 위해, 소규모 중앙집중식 열 네트워크에서 직팽식 태양열 히트펌프기반 분산형 열 프로슈머 구현 방안을 모색하였다. 본 연구를 위해 소규모 4세대 소규모 열네트워크가 구성되어 있는 진천 친환경에너지타운을 실증장소로 선정하였으며, 열 프로슈머 건물로 어린이집을 선정하였다. 시뮬레이션을 위해 1년간의 진천 친환경에너지타운의 외기온도, 경사면 일사량, 타운 내 급탕부하, 급탕 공급 열네트워크 온도등 운영실험 결과를 기반으로 열 프로슈머로의 역할과 에너지절감 가능성을 분석하였다. 이후 직팽식 태양열 히트펌프에 대한 운영 모사를 위해 기존 실험논문의 결과를 바탕으로 ANOVA 분석을 통해 직팽식 태양열 히트펌프의 COP를 예측할 수 있는 모델을 도출하였다. 본 모델의 R2값은 91.1%로 적정한 운영 예측이 가능할 것으로 판단되었다. 본 모델을 활용하여, 기존 진천 친환경에너지타운의 전력소비량 측정데이터와 직팽식 태양열 히트펌프의 적용 시 전력소비량 및 각 건물의 급탕 전기히터의 전력소비량을 산정하여 비교분석하였다. 그 결과, 직팽식 태양열 히트펌프가 열 프로슈머로 운영될 경우, 전체 타운 급탕에너지의 51.6%를 담당할 수 있는 것으로 나타났으며, 건물별 급탕에너지 소비량의 37.7%를 절감할 수 있을 것으로 예측되었다. 본 연구는 선행연구를 통해 도출된 실험결과를 바탕으로 직팽식 태양열 히트펌프를 모사할 수 있는 모델을 도출하였으나, 기후대의 차이 등으로 국내에서의 운영에 따른 COP는 다소 차이가 있을 수 있다. 특히, 도출된 모델의 시스템 용량과 시뮬레이션 대상 시스템의 용량 차이로 인한 COP는 차이가 발생할 수 있다. 이에, 추후연구에서는 직팽식 태양열 히트펌프를 실제 설치하여 운영결과에 대한 검증을 진행할 예정이다. 또한, 본 연구의 실증단지인 진천 친환경에너지타운은 저온 열네트워크로 구성되어 있으며, 열공급 대상건물이 일반 지역난방과 많은 차이가 있으므로, 본 연구를 기존 고온 지역난방에 적용은 다소 무리가 있을 것으로 판단된다. 이에, 향후 연구에서는 제안된 구성방식에 대한 경제성 분석이 고려되어야 하며, 고온 지역난방대비 4세대 저온 지역난방이 가지는 배관증 증대와 같은 문제들도 고려되어야 할 것이다.

온실 내외부 공기열의 선택적 축열에 의한 히트펌프 난방성능 개선

권진경(Jin Kyung Kwon),김승희(Seung Hee Kim),전종길(Jong Gil Jeon),강연구(Youn Koo Kang),장갑열(Kab Yeol Jang) (사)한국생물환경조절학회 2017 생물환경조절학회지 Vol.26 No.4

본 연구에서는 장미 재배온실을 대상으로 온실 내부의 태양잉여열과 외부의 공기열을 선택적 열원으로 이용하여 온실난방용 온수를 생산할 수 있는 공기 대 물 히트펌프의 설계와 성능시험을 수행하였다. 태양잉여열 이용축열운전과 외기열 이용 축열운전은 작물의 생육적온을 고려한 온실내부의 설정온도에 따라 자동전환 되도록 설계하였다. 제어반에 12개의 기준온도를 설정함으로써 축열운전 전환, 난방, 환기를 자동제어하며, 태양잉여열-외기열 선택적 축열운전에서 축열조의 온도는 축열능력과 난방부하에 대응하여 35~52℃로 3단계 변온제어 하였다. 태양잉여열-외기열 선택적 축열에서 태양잉여열 이용 축열은 전체 시간의 23.1%, 외기열 이용 축열은 30.7%, 히트펌프 휴지시간은 46.2%를 차지하였으며, 난방성능계수는 태양잉여열 이용 축열 시 3.83, 외기열 이용 축열시 2.77, 전체 3.24로 평가되었다. 비교시험을 위해 축열조 온도를 50~52℃로 항온제어 하는 조건에서 외기열 단독 이용 축열 시험을 수행하였으며 이때의 난방성능계수는 2.33으로 분석되었다. 결과적으로 공기 대 물 히트펌프의 열원으로 온실내부 태양잉여열과 외부 공기열을 병용하고, 축열조 온도를 변온제어 한 결과 일반적인 외기열 이용 축열운전과 축열조 항온제어에 비해 난방성능 계수가 39% 향상됨을 확인하였다. In this study, the design and performance test of the air to water heat pump capable of producing hot water for greenhouse heating by using the surplus solar heat inside the greenhouse and the air heat outside greenhouse as the selective heat source were conducted. The heat storage operations using the surplus solar heat and the outside air heat were designed to be switched according to the setting temperature of the greenhouse in consideration of the optimum temperature range of the crop. In the developed system, it was possible to automatically control the switching of heat storage operation, heating and ventilation by setting 12 reference temperatures on the control panel. In the selective heat storage operation with the surplus solar heat and outside air heat, the temperature of thermal storage tank was controlled variably from 35℃ to 52℃ according to the heat storage rate and heating load. The heat storage operation times using the surplus solar heat and outside air heat were 23.1% and 30.7% of the experimental time respectively and the heat pump pause time was 46.2%. COP(coefficient of performance) of the heat pump of the heat storage operation using the surplus solar heat and outside air heat were 3.83 and 2.77 respectively and was 3.24 for whole selective heat storage operation. For the comparative experiment, the heat storage operation using the outside air heat only was performed under the condition that the temperature of the thermal storage tank was controlled constantly from 50 to 52℃, and COP was analyzed to be 2.33. As a result, it was confirmed that the COP of the heat storage operation using the surplus solar heat and outside air heat as selective heat source and the variable temperature control of the thermal storage tank was 39% higher than that of the general heat storage operation using the outside air heat only and the constant temperature control of the thermal storage tank.

태양열 냉ㆍ난방 및 급탕 시스템 열성능

곽희열(Kwak Hee-Youl),주홍진(Joo Hong-Jin),이호(Lee Ho) 한국태양에너지학회 2009 한국태양에너지학회 학술대회논문집 Vol.- No.-

This paper presents demonstration study results derived through field testing of a solar assisted cooling and heating system for the library of a cultural center building located in Gwangju, Korea. The area of demanded cooling and heating for building was about 350㎡. Solar hot water was delivered by means of a 200㎡ array of evacuated tubular solar collector (ETSC) to drive a single-effect (LiBr/H2O) absorption chiller of 10RT nominal cooling capacity. From March in 2008 to February in 2009, demonstration test were performed for solar cooling and heating system. After experiments and analysis, this study found that solar thermal system was 84% for the solar hot water supply and 12% for space heating and 4% for space cooling.

Facade 일체형 태양열 집열기를 갖는 태양열/지열 하이브리드 시스템의 태양열 집열시스템 작동특성 연구

백남춘(Baek Nam-Choon),이진국(Lee Jin-Kook),유창균(Yu Chang-kyun),윤응상(Yoon Eung-Sang),윤종호(Yoon Jong-Ho) 한국태양에너지학회 2010 한국태양에너지학회 논문집 Vol.30 No.5

In this study, the solar thermal and geo-source heat pump(GSHP) hybrid system for heating and cooling of Zero Energy Solar House(ZESH) was analyzed by experiment. The GSHP in this hybrid system works like as aback-up device for solar thermal system. This hybrid system was designed and installed for Zero Energy Solar House (KIER ZeSH) in Korea Institute of Energy Research. The purpose of this study is to find out that this system is optimized and operated normally for the heating load of ZeSH. The analysis was conducted as followings ; -the thermal performance of facade integrated solar collector -the on/off characteristics of solar system and GSHP -the contribution of solar thermal system. -the performance of solar thermal and ground source heat pump system respectively. -the meet of thermal load (space and water heating load). This experimental study could be useful for the optimization of this system as well as its application in house. This hybrid system could be commercialized for the green home if it is developed to a package type.

해수냉열원을 이용한 태양열계간축열시스템의 건물냉방 적용에 관한 연구

김명래(Kim Myung-Rae),윤재옥(Yoon Jae-Ock) 한국태양에너지학회 2009 한국태양에너지학회 학술대회논문집 Vol.2009 No.11월

Paradigm depending only on fossil fuel for building heat source is rapidly changing. Accelerating the change, as it has been known, is obligation for reducing green house gas coming from use of fossil fuel, i.e. reaction to United Nations Framework Convention on Climate Change. In addition, factors such as high oil price, unstable supply, weapon of petroleum and oil peak, by replacing fossil fuel, contributes to advance of environmental friendly renewable energy which can be continuously reusable. Therefore, current new energy policies, beyond enhancing effectiveness of heat using equipments, are to make best efforts for national competitiveness. Our country supports 11 areas for new renewable energy including sun light, solar heat and wind power. Among those areas, ocean thermal energy specifies tidal power generation using tide of sea, wave and temperature differences, wave power generation and thermal power generation. But heat use of heat source from sea water itself has been excluded as non-utilized energy. In the future, sea water heat source which has not been used so far will be required to be specified as new renewable energy. This research is to survey local heating system in Europe using sea water, central solar heating plants, seasonal thermal energy store and to analyze large scale central solar heating plants in German. Seasonal thermal energy store necessarily need to be equipped with large scale thermal energy store. Currently operating central solar heating system is a effective method which significantly enhances sharing rate of solar heat in a way that stores excessive heat generating in summer and then replenish insufficient heat for winter. Construction cost for this system is primarily dependent on large scale seasonal heat store and this high priced heat store merely plays its role once per year. Since our country is faced with 3 directional sea, active research and development for using sea water heat as cooling and heating heat source is required for seashore villages and building units. This research suggests how to utilize new energy in a way that stores cooling heat of sea water into seasonal thermal energy store when temperature of sea water is its lowest temperature in February based on West Sea and then uses it as cooling heat source when cooling is necessary. Since this method utilizes seasonal thermal energy store from existing central solar heating plant for heating and cooling purpose respectively twice per year maximizing energy efficiency by achieving 2 seasonal thermal energy store, active research and development is necessarily required for the future.

태양광열 복합 시스템의 연구개발 동향 분석

김진희,이현주,양연원,김준태 대한건축학회지회연합회 2006 대한건축학회지회연합회 학술발표대회논문집 Vol.2 No.1

태양광열 복합 시스템은 건물에 필요한 열원과 전기를 동시에 생산하는 시스템이다. 이러한 시스템은 PV 패널 후면의 열을 제거하여 PV 모듈의 효율을 극대화하고 이 폐열을 이용하여 건물 난방에 이용하는 복합적인 기능을 수행하는 시스템으로 활용하는 것이 중요하다. 본 연구에서는 태양광과 태양열을 동시에 활용한 태양광열 복합시스템에 대해 알아보고, 이와 관련된 국내외 연구동향에 대해 살펴보았다. 따라서 국내에 태양광열 복합시스템을 건물난방에 적용하기 위한 기초 연구자료로 활용하고자 한다. Photovoltaic-solar thermal combined system produces electricity and thermal energy which are necessary to buildings. The system removes heat from the PV module that would help to raise the efficiency of the PV system's performance. It is useful to utilize the waste heat for building space heating as this multi-functional application of solar energy system will improve the viability of the system. This paper describes research and development trends of PV-solar thermal combined systems. It is believed that this analysis will provide valuable source of information about the PV-solar thermal combined system to apply into building space heating.

태양광 추적기반의 파라볼릭을 이용한 태양열 집열장치 프로토타입에 관한 연구

정세훈,김종호,심춘보,박성균 한국전자통신학회 2016 한국전자통신학회 논문지 Vol.11 No.4

Efforts have continued in recent years to research and develop new alternative energy sources to replace coal and oil. These days interest is exploding in new pollution-free renewable energy due to the rising prices of finite energy sources. In the field of solar energy, one of new renewable energy that has been actively researched and commercialized, research efforts have been focused on solar light energy, whose efficiency has, however, reached a saturation point already. Thus, this paper proposed a solar tracking-type parabolic heat collection device to utilize solar thermal energy rather than solar light energy. The proposed device was designed in a parabolic form to collect solar heat effectively. The investigator made its prototype by incorporating a five-axis censor-based solar tracking technology in it to sense changes to the location of the sun according to the seasons and periods. In addition, an administrator interface was designed and implemented for the efficient management of heat collection device. 석탄과 석유를 대신할 새로운 대체 에너지의 연구 및 개발은 지난 수년간 계속해서 연구되고 있다. 최근엔 유한 에너지 가격 상승으로 인하여 무공해 신재생 에너지의 관심이 증가하고 있다. 특히 기존에 활발히 연구되고 상용화된 신재생 에너지 분야 중 태양에너지는 태양광 에너지에 주된 연구가 이루어져 있다. 그러나 태양광 에너지의 효율성은 이미 포화상태에 도달하였다. 이에 본 논문에서는 태양광이 아닌 태양열 에너지를 활용할 수 있는 태양광 추적형 파라볼릭 집열장치를 제안한다. 제안하는 태양열 집열장치는 효과적으로 태양열을 집열하기 위하여 파라볼릭 형태로 제안하고, 계절 및 시기에 따른 태양의 위치변화를 감지할 수 있도록 5축 센서 방식의 태양광 추적형 트래킹 기술을 결합한 태양열 집열장치의 프로토타입을 제안한다. 또한 집열장치의 효율적인 관리를 위하여 관리자 인터페이스를 설계 및 구현한다.

핀-튜브 열교환 구조를 갖는 복합집열기에서 핀 높이 및 간격에 따른 공기열 이용 액체 가열 성능에 관한 수치해석 연구

최휘웅(Choi Hwi-Ung),파쿠르 로커만(Fatkhur Rokhman),류남진(Lyu Nam-Jin),윤정인(Yoon Jung-In),손창효(Son Chang-Hyo),최광환(Choi Kwang-Hwan) 한국태양에너지학회 2016 한국태양에너지학회 논문집 Vol.36 No.3

Solar assisted heat pump system uses solar thermal energy as a heat source of evaporator of heat pump. So, COP can be enhanced as well as collector efficiency. For improving performance of this system, some research about hybrid solar collector that has fin-and-tube heat exchanger has been conducted. This collector can get a thermal energy from ambient air for liquid heating, so heated liquid can be used as a heat source of evaporator in heat pump even the solar radiation is not enough. In this study, numerical analysis was conducted for confirming heat gain of liquid according to fin height and pitch of fin-and-tube heat exchanger in collector. As a result, higher heat gain was obtained on lower fin height and narrow fin pitch, but the pressure drop also increased with increment of heat gain. Thus the JF factor considering both heat transfer enhancement and pressure drop was investigated and the maximum value was shown when the fin height and pitch were 40mm and 45mm. So it is considered that this installation condition has a highest heat transfer improvement when comparing with pressure drop. However heat gain of liquid at this condition was less than the other installation conditions of fin pitch on same height. Then, after establishing a proper minimum heat gain of liquid, actual production and experiment of collector will be conducted with fin height and pitch showing maximum JF factor and satisfying selected minimum heat gain of liquid on the basis of results of this study.

온수 급탕 및 난방을 위한 히트 펌프 태양열 시스템의 성능 분석

손진국(Sohn Jin-Gug) 한국태양에너지학회 2018 한국태양에너지학회 논문집 Vol.38 No.5

This study aims to analyze the performance of solar thermal system with heat pump for domestic hot water and heat supply. There are four types of system. Systems are categorized based on the existence of a heat pump and the ways of controlling the working fluid circulating from the collector. Working fluid is controlled by either temperature level (categorized as system 1 and 2) or sequential flow (system 3 and 4). Heat balance of the system, the solar fraction, hot water and heating supply rates, and performance of heat pump are analyzed using TRNSYS and TESS component programs. Technical specifications of the main facilities are as follow; the area of the collector to 25 ㎡, the volumes of the main tank and the buffer tank to 0.5 ㎥ and 0.8 ㎥, respectively. Heating capacity of the heat pump in the heating mode is set to 30,000 kJ / hr. Hot water supply set 65 liters per person each day, total heat transfer coefficient of the building to 1,500 kJ / kg.K. Indoor temperature is kept steadily around 22℃. The results are as follows; 6 months average solar fraction of system 1 turns out to be 39%, which is 6.7% higher than system 2 without the heat pump, indicating a 25% increase of solar fraction compared to that of system 2. In addition, the solar fraction of system 1 is 2% higher than that of system 3. Hot water and heating supply rate of system 1 are 93% and 35%, respectively. Considering the heat balance of the system, higher heat efficiency, and solar fraction, as whole, it can be concluded that system 1 is the most suitable system for hot water and heat supply.